Stokes Number Analysis of the Moving Droplets in the Steam-Water Separator

2018 ◽  
Author(s):  
Fulong Zhao ◽  
Qianfeng Liu ◽  
Chenru Zhao ◽  
Hanliang Bo ◽  
Ying Liu ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Separation Efficiency ◽  
Stokes Number ◽  
Separation Performance ◽  
Power Station ◽  
Wave Type ◽  
Water Separator ◽  
Vapor Stream ◽  
Critical Separation ◽  
Separation Size

The steam-water separator is vitally important equipment to remove the droplets entrained by the vapor stream to provide dry saturated steam for the steam turbine in the nuclear power station. With the development of the large nuclear power station and the vessel nuclear power plant, the steam-water separation performance should be more efficient under the condition of higher pressure, power load and circulating ratio. The droplet motion model, which is solved by typical four steps Runge-Kutta method and validated against the experimental results, is developed according to the physical phenomenon description and the mechanism comprehension of the vapor entrained droplets moving in the wave-type vanes separator. The Euler-Lagrange methodology is adopted to simulate the moving droplet entrained by the vapor stream in the wave-type vanes separator and the separation performance is investigated. The separation efficiency of the separator and motion trajectories of droplets with various sizes are presented. Stokes Number (St) of diverse droplets is obtained to analyze the influence of Stokes Number on the moving droplets trajectories and the separation efficiency. The results reveal that the values of Stokes Number for most of the moving droplets in the wave-type vanes separator are beyond 1, which indicates that most of droplets are likely to collide with the solid wall of the separator. Only when the droplet velocity is smaller than 1 m/s or the droplet radius is less than 2 μm, the Stokes Number may be below 1 and the moving droplets can be entrained by the stream flow until escaping from the separator. The analysis can forecast the maximum critical separation size of the droplets that cannot be removed, and the minimum critical separation size of the droplets that can be removed throughly by the separator and guide the design of the separator.

Influence of Working Pressure and Pressure Difference on Static Droplet Evaporation Characteristics

2017 ◽  
Author(s):  
Fulong Zhao ◽  
Chenru Zhao ◽  
Hanliang Bo ◽  
Ying Liu
Keyword(s):  
Water Vapor ◽  
Pressure Difference ◽  
Nuclear Power ◽  
Evaporation Rate ◽  
Droplet Evaporation ◽  
Droplet Surface ◽  
Power Station ◽  
Working Pressure ◽  
Water Separation ◽  
Water Separator

The function of steam separator is to remove the small droplets carried by the vapor stream and to provide qualified saturated vapor for the steam turbine in the nuclear power station. The separating characteristics of the steam-water separation plant are of vital importance to the safe operation, economy as well as reliability of the power station. In order to satisfy the requirement of power increase of large nuclear power station as well as space compaction of the vessel power plant, the steam vapor quality must be improved, which requires that the steam-water separator has better separating function to make sure that it can provide the qualified steam on the condition of higher steam pressure, power load as well as circulating ratio. There are many complex phenomena when the droplet moves in the steam-water separating plant, including the droplet emergence, the droplet moving with steam vapor, the collision between droplets and with solid wall, evaporation. It is a good way to study the steam-water separating characteristics for the microcosmic behavior of the droplet. Thus, in order to know the droplet evaporation characteristics in the steam-water separator, the static droplets phase transformation model under the pressure variation condition is built according to the physical phenomenon description and mechanism comprehension when the droplet moves with the steam vapor in the steam-water separation plants. This model is solved by the typical four steps Runge-Kutta method and validated by comparing with the experimental results. Then, the influence of working pressure as well as pressure difference between the droplet surface and the environment on the static droplet evaporation characteristics is conducted. The simulation results show that the working pressure and pressure difference have great impact on the static droplet evaporation characteristics. With the increase of the working pressure, the droplet evaporation rate becomes slower, that is because the physical property parameters of the water vapor and water become closer to each other and the self-diffusion coefficient of the water vapor as well as the evaporation condensation coefficient become smaller, which results in the droplet evaporation rate becomes slower. When the pressure difference between the droplet surface and the environment rises, the droplet evaporates faster, that is because the vapor velocity around the droplet becomes larger and the droplet evaporates faster. These results of the simulation can lay the foundation for subsequent study of the droplet evaporation characteristics when the droplet moving in the separating plants and for the droplet fast evaporation characteristics when the environment pressure changes fast.

Efficiency Comparisons for a Centrifugal Separator Using Hydrocarbon Fluids and Steam and Water

1999 ◽  
Vol 121 (2) ◽  
pp. 117-121 ◽  
Author(s):  
D. P. Birmingham ◽  
W. H. Hall
Keyword(s):  
Simple Model ◽  
Nuclear Power ◽  
Separation Efficiency ◽  
Centrifugal Separator ◽  
Liquid Separation ◽  
Hydrocarbon Production ◽  
Second Stage ◽  
Water Separator ◽  
Efficiency Data ◽  
Production Industry

During 1996 and 1997, a steam and water separator used in the nuclear power industry was tested with hydrocarbon fluids to evaluate its potential for use in the hydrocarbon production industry. Prior to testing with hydrocarbon fluids, a nondimensional parameter was developed from a simple model of the second-stage centrifugal separator to correlate existing liquid separation efficiency data for this separator using steam and water. This paper outlines the development of the nondimensional correlating parameter and presents comparisons of liquid separation efficiency with steam and water and hydrocarbon fluids using this parameter.

Numerical Simulation Analysis of Corrugated Plate With Hook

2017 ◽  
Author(s):  
Bowen Chen ◽  
Ruifeng Tian ◽  
Feng Mao ◽  
Wei He
Keyword(s):  
Pressure Drop ◽  
Steam Turbine ◽  
Steam Generator ◽  
Nuclear Power ◽  
High Efficiency ◽  
Separation Efficiency ◽  
Simulation Analysis ◽  
Saturated Steam ◽  
System Pressure ◽  
Water Separator

Separation device is one of the important equipment in the steam generator, which reduce the humidity, and it is a key device of nuclear plant which can guarantee the saturated steam to the steam turbine to provide clean. In nuclear power plant, the nuclear steam turbine uses saturated steam directly, so the separation system in steam generator requires a high efficiency of separation. Because of its simple process, high separation efficiency, low system pressure drop and large capacity, small volume, long life and other advantages, corrugated plate in water separator technology is more and more extensive application in the production process. In this paper, the corrugated plate water separator is simulated research, through the establishment of a two-dimensional model of corrugated plate, separation efficiency and pressure drop of corrugated plate is simulated. By setting the different air speed, different gap of hook-plate, observe the change of the pressure drop and separation efficiency, and analyzes the internal mechanism of the foundation for the optimization of corrugated plate dryer.

Field testing CFD-based predictions of storage chamber gross solids separation efficiency

1999 ◽  
Vol 39 (9) ◽  
pp. 161-168 ◽  
Author(s):  
Virginia R. Stovin ◽  
Adrian J. Saul ◽  
Andrew Drinkwater ◽  
Ian Clifforde
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Settling Velocity ◽  
Separation Efficiency ◽  
Flow Patterns ◽  
Total Efficiency ◽  
Separation Performance ◽  
Storage Chamber ◽  
Solids Separation ◽  
Simulated Flow

The use of computational fluid dynamics-based techniques for predicting the gross solids and finely suspended solids separation performance of structures within urban drainage systems is becoming well established. This paper compares the result of simulated flow patterns and gross solids separation predictions with field measurements made in a full size storage chamber. The gross solids retention efficiency was measured for six different storage chambers in the field and simulations of these chambers were undertaken using the Fluent computational fluid dynamics software. Differences between the observed and simulated flow patterns are discussed. The simulated flow fields were used to estimate chamber efficiency using particle tracking. Efficiency results are presented as efficiency cusps, with efficiency plotted as a function of settling velocity. The cusp represents a range of efficiency values, and approaches to the estimation of an overall efficiency value from these cusps are briefly discussed. Estimates of total efficiency based on the observed settling velocity distribution differed from the measured values by an average of ±17%. However, estimates of steady flow efficiency were consistently higher than the observed values. The simulated efficiencies agreed with the field observations in identifying the most efficient configuration.

Sign in / Sign up

Export Citation Format

Share Document